(a) Field of the invention
The present invention relates to program type electric shutters, and more particularly to a flash synchronization controlling means for program type electric shutters wherein the flash synchronizing action is made to be electronically controlled.
(B) Description of the prior art
There are program type electric shutters wherein the opening action of shutter blades is retarded so that the shutter blade opening characteristic curve may be made triangular and wherein the size of the opening of shutter blades is detected while the release button of the camera is pushed and the shutter is actually released so that the shutter blades may quickly open to a predetected opening position when the shutter is released and the shutter blade opening characteristic curve may be made trapezoid.
In this kind of program type electric shutter, anyhow, as the size of the opening formed by the shutter blades in photographing is automatically determined in response to the brightness of the object to be photographed in such case, in order to make the peak of the lighting of the flashing device coincide with the fully opened position of the blades, in the case of controlling the ignition time of the flashing device with a mechanical synchro-contact, the closing time of the synchro-contact must be moved in response to the size of the opening to be controlled. Therefore, in such system, there have been defects that the mechanical constitution is very complicated and that the synchronizing operation itself is unstable.